783 research outputs found
Fern Reproduction at Woodman Hollow, Central Iowa: Preliminary Observations and a Consideration of the Feasibility of Studying Fern Reproductive Biology in Nature
Field observations of spore availability, gametophyte establishment and survival, and sporophyte production were made over a one-year period. Maximum spore release for most species occurred shortly after spore maturation in mid to late summer, but some spores remained on sporophyte fronds through the winter and were available for germination the following spring. Gametophytes of Cystopteris fragilis, Woodsia obtusa and Adiantum pedatum became established in late summer and fall. Production of sporophytes occurred both in fall and in the following spring. Both gametophytes and juvenile sporophytes survived the winter in relatively unchanged condition. Results indicate that it is feasible and important to correlate field studies with current laboratory studies of fern reproductive biology
HI Detection in two Dwarf S0 Galaxies in Nearby Groups: ESO384-016 and NGC 59
An \hi survey of 10 dE/dS0 galaxies in the nearby Sculptor and Centaurus A
groups was made using the Australia Telescope Compact Array (ATCA). The
observed galaxies have accurate distances derived by Jerjen et al (1998; 2000b)
using the surface brightness fluctuation technique. Their absolute magnitudes
are in the range . Only two of the ten galaxies were
detected at our detection limit ( \msol for the Centaurus
group and \msol for the Sculptor group), the two dS0
galaxies ESO384-016 in the Centaurus A Group and NGC 59 in the Sculptor Group,
with \hi masses of \msol and \msol respectively. Those two detections were confirmed using the Green
Bank Telescope. These small \hi reservoirs could fuel future generations of low
level star formation and could explain the bluer colors seen at the center of
the detected galaxies. Similarly to what is seen with the Virgo dEs, the two
objects with \hi appear to be on the outskirt of the groups.Comment: 25 pages (11 figures), accepted by A
Comments on the distribution of \u3ci\u3eBotrychium lunarioides\u3c/i\u3e (Ophioglossaceae) in Texas
Botrychium lunarioides (Michx.) Sw. (Ophioglossaceae) is now known to be widespread and abundant throughout the eastern portion of Texas. In 1996, Do, et al. reported ten additional county records in the central portion of the Post Oak Savannah of Texas, thereby extending the known distribution of the species up to 273 km to the west. Additional field studies during 1996 have yielded nineteen new county records for the species in Texas. These new reports are primarily from the Post Oak Savannah, Pineywoods, and Blackland Prairies of northeast Texas and from the southern portion of the Post Oak Savannah. The most notable occurrence of the species is at Lake Bastrop State Recreation Area, Bastrop County, about 45 km ESE of Austin, which extends both the western and southern known limits of the species
A Wide-field High Resolution HI Mosaic of Messier 31: I. Opaque Atomic Gas and Star Formation Rate Density
We have undertaken a deep, wide-field HI imaging survey of M31, reaching a
maximum resolution of about 50 pc and 2 km/s across a 95x48 kpc region. The HI
mass and brightness sensitivity at 100 pc resolution for a 25 km/s wide
spectral feature is 1500 M_Sun and 0.28 K. Our study reveals ubiquitous HI
self-opacity features, discernible in the first instance as filamentary local
minima in images of the peak HI brightness temperature. Local minima are
organized into complexes of more than kpc length and are particularly
associated with the leading edge of spiral arm features. Just as in the Galaxy,
there is only patchy correspondence of self-opaque features with CO(1-0)
emission. Localized opacity corrections to the column density exceed an order
of magnitude in many cases and add globally to a 30% increase in the atomic gas
mass over that inferred from the integrated brightness under the usual
assumption of negligible self-opacity. Opaque atomic gas first increases from
20 to 60 K in spin temperature with radius to 12 kpc but then declines again to
20 K beyond 25 kpc. We have extended the resolved star formation law down to
physical scales more than an order of magnitude smaller in area and mass than
has been possible previously. The relation between total-gas-mass- and
star-formation-rate-density is significantly tighter than that with
molecular-mass and is fully consistent in both slope and normalization with the
power law index of 1.56 found in the molecule-dominated disk of M51 at 500 pc
resolution. Below a gas-mass-density of about 5 M_Sun/pc^2, there is a
down-turn in star-formation-rate-density which may represent a real local
threshold for massive star formation at a cloud mass of about 5x10^4 M_Sun.Comment: Accepted for publication in ApJ, 34 pages, 20 figure
Reaction time variability in children with ADHD symptoms and/or dyslexia.
Reaction time (RT) variability on a Stop Signal task was examined among children with attention deficit hyperactivity disorder (ADHD) symptoms and/or dyslexia in comparison to typically developing (TD) controls. Children's go-trial RTs were analyzed using a novel ex-Gaussian method. Children with ADHD symptoms had increased variability in the fast but not the slow portions of their RT distributions compared to those without ADHD symptoms. The RT distributions of children with dyslexia were similar to those of TD-controls. It is argued that variability in responding may be underpinned by impairments in response preparation or timing during Stop Signal tasks
Strong peoples - strong country: Indigenous heritage monitoring framework summary report
The report titled 'Monitoring Indigenous Heritage within the Reef 2050 Integrated Monitoring and Reporting Program: Final report of the Indigenous Heritage Expert Group' can be viewed through this repository at http://hdl.handle.net/11017/3535This is a summary report of the Strong peoples – Strong country framework, which details information on the framework. The methodology and processes of the expert group are found in, Monitoring Indigenous Heritage within the Reef 2050 Integrated Monitoring and Reporting Program: Final report of the Indigenous Heritage Expert Group (Jarvis, Hill, Buissereth et al. 2019). This summary presents the key elements of the Indigenous heritage monitoring framework for the Great Barrier Reef: Strong peoples – Strong country. It's been extracted from the Indigenous Heritage Expert Group report, which outlines a proposed design for monitoring of the Indigenous heritage theme under the Reef 2050 Integrated Monitoring and Reporting Program
Monitoring the Indigenous heritage within the Reef 2050 Integrated Monitoring and Reporting Program: final report of the Indigenous Heritage Expert Group
An accessible copy of this report is not yet available from this repository, please contact [email protected] for more information
Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition
Ca(FeRh)As undergoes successive phase transitions with
increasing Rh doping in the 0 limit. The antiferromagnetic-metal phase
with orthorhombic structure at 0.00 0.020 is driven to a
superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020
0.024; a non-superconducting collapsed-tetragonal (cT) phase
takes over at 0.024. The breakdown of Fermi-liquid transport is
observed in the ucT phase above . In the adjacent cT phase,
Fermi-liquid transport is restored along with a disappearance of
superconductivity. This interplay of superconductivity and Fermi-liquid
transport suggests the essential role of magnetic fluctuations in the emergence
of superconductivity in doped CaFeAs.Comment: 11 pages, 4 figure
Radio-Continuum study of the Nearby Sculptor Group Galaxies. Part 1: NGC 300 at lambda = 20 cm
A series of new radio-continuum (lambda=20 cm) mosaic images focused on the
NGC 300 galactic system were produced using archived observational data from
the VLA and/or ATCA. These new images are both very sensitive (rms=60 microJy)
and feature high angular resolution (<10"). The most prominent new feature is
the galaxy's extended radio-continuum emission, which does not match its
optical appearance. Using these newly created images a number of previously
unidentified discrete sources have been discovered. Furthermore, we demonstrate
that a joint deconvolution approach to imaging this complete data-set is
inferior when compared to an immerge approach.Comment: 13 pages, 12 figures, accepted to APSS, new version to correct the
missing reference
Pressure effects on superconducting properties of single-crystalline Co doped NaFeAs
Resistivity and magnetic susceptibility measurements under external pressure
were performed on single-crystals NaFe1-xCoxAs (x=0, 0.01, 0.028, 0.075,
0.109). The maximum Tc enhanced by pressure in both underdoped and optimally
doped NaFe1-xCoxAs is the same, as high as 31 K. The overdoped sample with x =
0.075 also shows a positive pressure effect on Tc, and an enhancement of Tc by
13 K is achieved under pressure of 2.3 GPa. All the superconducting samples
show large positive pressure coefficient on superconductivity, being different
from Ba(Fe1-xCox)2As2. However, the superconductivity cannot be induced by
pressure in heavily overdoped non-superconducting NaFe0.891Co0.109As. These
results provide evidence for that the electronic structure is much different
between superconducting and heavily overdoped non-superconducting NaFe1-xCoxAs,
being consistent with the observation by angle-resolved photoemission
spectroscopy.Comment: 6 pages, 6 figure
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